The present invention relates to controllers and more particularly to current mode pulse width modulation (PWM) controllers for providing output regulated control.
There is presently a need for a single integrated dual current mode switching regulator circuit. For example, remote controlled television sets often require multiple switching regulators for driving high and low power supplies. The low voltage power supply is utilized to provide low power output to drive the remote control circuit which must be on in order to respond to the users remote control unit while the high power supply, which drives the television receiver and cathode ray tube, is only turned on when the television set is turned on by the user.
Prior art current mode switching regulator integrated circuits do not provide dual channel operation. Multiple output power supplies have been built in the past with separate PWM regulator integrated circuits driven by external circuitry to synchronizes the switching regulators to a common oscillator. However, these prior art systems have suffered in that unwanted crosstalk or interference between the two regulator channels occur. This crosstalk results in a spike occurring in one of the two channels that can cause early turn off of the other of the two channels. This is highly undesirable because it causes output instability.
Hence, a need exists for a dual current mode switching regulator that is economical and which can provide dual output regulation without suffering from the problems of the prior art.